Heaters are currently being used for a vast amount of applications. One such application is during sterilizing of packaging materials in a filling machine being configured to convert a web of packaging material into a series of individual packages enclosing liquid food.
In such application, sterilizing of the packaging material prior to filling may be performed by feeding the packaging material through a bath of hydrogen peroxide. Exposing the packaging material to hydrogen peroxide with subsequent heating will kill all unwanted micro-organisms, since heating will increase the sterilizing effect of the hydrogen peroxide. Heating does not only provide for efficient sterilizing, but also provides an additional effect by drying the packaging material before sealing and filling the individual packages.
For this purpose heaters are normally provided whereby sterile air, or other suitable hygienic gases, is heated before flowing over the surface area of the sterilized packaging material.
In practice, the web of packaging material is running fast through the sterilizing bath whereby it is necessary to have efficient heaters being capable of heating the gas flow to its required temperature in short time. However, should there be a situation when the heaters are needed to be shut off it is desired to provide fast cooling of the heaters, as well as of the packaging material inside the sterilizing unit in order to avoid damage of the packaging material.
Previously this problem has been solved by providing a separate cooling system being configured to spray a mist of cold sterile water onto the packaging material while the heaters are cooling down. Such solution however requires additional components leading to increased complexity and costs. There is thus need for an improved heater which does not damage an adjacent packaging material upon shut-off.